When a workpiece is sliced into wafers with a wire saw, slicing is performed so that the sliced plane has a predetermined orientation. The slicing method begins with measuring an axis orientation of the workpiece while holding and fixing the workpiece with a workpiece holder. On the basis of the data of the measured axis orientation, the workpiece holder is fixed to a wire saw, the workpiece position is adjusted, and the workpiece is then sliced such that the crystal axis orientation of the workpiece coincides with a desired plane orientation of the wafer. The plane orientation of the sliced plane of the workpiece is adjusted by a combination of a rotating motion around an axis perpendicular to a central axis between the bottoms of the cylindrical workpiece in a plane parallel to the wire row and a swinging motion of the central axis between the bottoms relative to the wire row plane. Such a method for adjusting a crystal plane orientation of a workpiece is referred to as an internal setup manner.
In slicing of a workpiece, it has been known that making a wire travel at an angle furthest from a crystal habit line such as a notch and an OF (Orientation Flat) to slice the workpiece is effective in inhibiting cracks and other detects of wafers (see Patent Document 1).
In addition to the internal setup manner, there is an external setup manner in which, when a workpiece is fixed to a workpiece holder, the orientation is adjusted by rotation of the workpiece around a central axis passing through midpoints of bottoms of the workpiece and pivot in a plane parallel to the wire row plane. In the external setup manner, a plane orientation of the workpiece is not adjusted in the wire saw.
By contrast, the internal setup manner enables a fixed position of a workpiece always to be located at an equivalent position in view of crystallography of the workpiece, and enables a product sliced out from the workpiece to be processed in an arrangement in which breakage is the hardest to occur. Especially, a silicon single crystal has an arrangement of cleavage plane for each crystal axis orientation, which can be known from a relative position between an OF or a notch and a central axis passing through midpoints of the bottoms.